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Lin, F.

Publications and source records attributed to Lin, F..

At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Beam Dynamics Study in a Dual Energy Storage Ring for Ion Beam Cooling

A dual energy storage ring designed for beam cooling consists of two closed rings with significantly different energies: the cooling and damping rings. These two rings are connected by an energy recovering superconducting RF structure that provides the necessary energy difference. In our design, the RF acceleration has a main linac and harmonic cavities both running at crest that at first accelerates the beam from low energy E_{L} to high energy E_{H} and then decelerates the beam from E_{H} to E_{L} in the next pass. The purpose of the harmonic cavities is to extend the bunch length in a dual energy storage ring as such a longer bunch length may be very useful in a cooling application. Besides these cavities, a bunching cavity running on zero-crossing phase is used outside of the common beamline to provide the necessary longitudinal focusing for the system. In this paper, we present a preliminary lattice design along with the fundamental beam dynamics study in such a dual energy storage ring.

Dhital, B.↗
DOE OSTI2021

The RCS Design Status for the Electron Ion Collider

The design of the Electron-Ion Collider Rapid Cycling Synchrotron (RCS) to be constructed at Brookhaven National Laboratory is advancing to meet the injection requirements for the Electron Storage Ring (ESR). Over the past year activities are focused on developing the approach to inject two 28 nC bunches every second, up from the original design of one 10nC bunch every second. The solution requires several key changes concerning the injection and extraction kickers, charge accumulation via bunch merging and a carefully calibrated RF acceleration profile to match the longitudinal emittance required by the ESR.

Ranjbar, V. H.↗
DOE OSTI2019

Endovascular Extra-Anatomic Femoro-Popliteal Bypass for Limb Salvage in Chronic Critical Limb Ischemia

Purpose: To report the initial clinical experience with fully endovascular extra-anatomic femoro-popliteal bypass (FPB) for limb salvage in patients with critical limb ischemia (CLI) and no traditional endovascular or surgical revascularization options. Methods: Between June 2013 and May 2018, endovascular procedure was proposed for limb salvage during multidisciplinary team meeting in fifteen hospitalized patients (median age 67 years; 73% men) with CLI and a high risk of major amputation. Primary outcome was amputation-free survival at 1 year. Secondary outcomes included mortality, cardiovascular (CV) events and major limb amputation at 1 year, primary/secondary bypass patency and wound healing at the last follow-up visit. Procedure-related complications (deaths, CV events, hemorrhages) were recorded through 30 days. Results: Technical procedure success rate was 100%. Major peri-procedural outcomes occurred in two patients (13%): One patient died secondary to cardiogenic shock; one patient suffered acute coronary syndrome associated with iliopsoas bleeding. No major amputation occurred through 30 days. Median follow-up period was 21.5 (18.25–45.5) months (last follow-up visits on April 2019). Amputation-free survival at 1-year and at the last follow-up visit was 80% and 53%, respectively. Cumulative mortality at 1-year and at the last follow-up visit was 13% and 33%, respectively. Primary and secondary bypass patency was 27% and 60%, respectively. Complete wound healing was achieved in 11 patients (73%). Conclusion: Endovascular extra-anatomic FPB represents an innovative approach for limb salvage in CLI with no traditional endovascular or surgical revascularization options. Our clinical experience highlights that this technique remains challenging because of frequent comorbidities and fragility of this patient population. Level of Evidence: Level 4, Case series.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

EQUILIBRIA AND SYNCHROTRON STABILITY IN TWO ENERGY STORAGE RINGS

In a dual energy storage ring, the electron beam passes through two loops at markedly different energies EL, and E_H, i.e., energies for low energy loop and high energy loop respectively. These loops use a common beamline where a superconducting linac at first accelerates the beam from EL to EH and then decelerates the beam from EH to EL in the next pass. There are two basic solutions to the equilibrium problems possible, i.e., ?Storage Ring? (SR) equilibrium and ?Energy Recovery Linac? (ERL) equilibrium. SR equilibrium mode more resembles the usual single loop storage ring with strong synchrotron motion and ERL equilibrium mode is the case where RF in two beam passes nearly cancels. Calculations based on linear transfer matrix formalism show that longitudinal stability exists for both SR mode and ERL mode in two energy storage rings.

Morozov, V. S.↗
DOE OSTI2019

Dynamic Aperture of JLEIC Electron Collider Ring with Errors and Correction

Design of the electron and ion rings of the Jefferson Lab Electron-Ion Collider (JLEIC) features the low-beta Interaction Regions (IR) with detector solenoid, non-linear chromaticity compensation blocks (CCB), and spin rotator optics with solenoids. The high beta functions in the IR final focus quadrupoles (FFQ) and in the CCB magnets result in strong effects of errors in these magnets. Performance of the spin rotators may also be sensitive to the errors. The first part of this study includes the design of orbit correction system for both rings and evaluation of dynamic aperture (DA) with misalignment and the correction. The second part is devoted to the DA study with the FFQ non-linear field errors. The orbit correction design, the dynamic aperture, and the impact on error specifications are presented.

Lin, F.↗
DOE OSTI2019

EXPERIMENTAL VERIFICATION OF TRANSPARENT SPIN MODE IN RHIC

High electron and ion polarizations are some of the key design requirements of a future Electron Ion Collider (EIC). The transparent spin mode, a concept inspired by the figure 8 ring design of JLEIC, is a novel technique for preservation and control of electron and ion spin polarizations in a collider or storage ring. It makes the ring lattice "invisible" to the spin and allows for polarization control by small quasi-static magnetic fields with practically no effect on the beam’s orbital characteristics. It offers unique opportunities for polarization maintenance and control in Jefferson Lab’s JLEIC and in BNL’s eRHIC. The transparent spin mode has been demonstrated in simulations and we now plan to test it experimentally. We present a design of an experiment using a polarized proton beam stored in one of the RHIC rings. In the experiment, one of the RHIC rings is configured in the transparent spin mode by aligning the axes of its two Siberian snakes. The experiment goals, procedures, hardware requirements and expected results are presented.

Morozov, V.S.↗
DOE OSTI2019

FULL ACCEPTANCE INTERACTION REGION DESIGN OF JLEIC

Nuclear physics experiments envisioned at a proposed future Electron-Ion Collider (EIC) require high luminosity of 10^33-10^34 cm^-2s^-1 and a full-acceptance detector capable of reconstruction of a whole electron-ion collision event. Due to a large asymmetry in the electron and ion momenta in an EIC, the particles associated with the initial ion tend to go at very small angles and have small rigidity offsets with respect to the initial ion beam. They are detected after they pass through the apertures of the final focusing quadrupoles. Therefore, the apertures must be sufficiently large to provide the acceptance required by experiments. In addition, to maximize the luminosity, the final focusing quadrupoles must be placed as close to the interaction point as possible. A combination of these requirements presents serious detection, optics and engineering design challenges. We present a design of a full-acceptance interaction region of Jefferson Lab Electron-Ion Collider (JLEIC). The paper presents how this design addresses the above requirements up to an ion momentum of 200 GeV/c. We summarize the magnet parameters, which are kept consistent with the Nb-Ti superconducting magnet technology.

Morozov, V.S.↗
DOE OSTI2019

Spin response function for spin transparency mode of RHIC

In the Spin Transparency (ST) mode of RHIC, the axes of its Siberian snakes are parallel. The spin tune in the ST mode is zero and the spin motion becomes degenerate: any spin direction repeats every particle turn. In contrast, the lattice of a conventional collider determines a unique stable periodic spin direction, so that the collider operates in the Preferred Spin (PS) mode. Contributions of perturbing magnetic fields to the spin resonance strengths in the PS mode are usually calculated using the spin response function. However, in that form, it is not applicable in the ST mode. This paper presents a response function formalism expanded for the ST mode of operation of conventional colliders with two identical Siberian snakes in the highly-relativistic limit. We present calculations of the spin response function for RHIC in the ST mode.

Morozov, V. S.↗
DOE OSTI2019

BEAM-BEAM EFFECT: CRAB DYNAMICS CALCULATION IN JLEIC

The electron and ion beams of a future Electron Ion Collider (EIC) must collide at an angle for detection, machine and engineering design reasons. To avoid associated luminosity reduction, a local crabbing scheme is used where each beam is crabbed before collision and de-crabbed after collision. The crab crossing scheme then provides a head-on collision for beams with a non-zero crossing angle. We develop a framework for accurate simulation of crabbing dynamics with beam-beam effects by combining symplectic particle tracking codes with a beam-beam model based on the Bassetti-Erskine analytic solution. We present simulation results using our implementation of such a framework where the beam dynamics around the ring is tracked using Elegant and the beam-beam kick is modeled in Python.

Morozov, V. S.↗
DOE OSTI2019

Update on the JLEIC Electron Collider Ring Design

The design concept of electron collider ring in the Jefferson Lab Electron-Ion Collider (JLEIC) is based on a small beam size at the interaction point (IP) to boost the luminosity. With a chosen beta-star at the IP, electron beam size is determined by the equilibrium emittance obtained by the linear optics design. In this paper, we present an update on the lattice design of the electron ring considering not only preservation of low beam emittance, but also optimization of geometric arrangement. In particular, recently development of the lattice design has been focused on incorporating the vertical dogleg, which brings the electron beam to the ion beam plane for collisions, in the spin rotator design. The vertical dogleg is designed with no horizontal emittance growth, controlled vertical emittance and no first-order effect on the electron polarization. Single particle nonlinear beam dynamics study is also performed to explore the momentum acceptance and dynamic aperture in this updated design.

Lin, F.↗
DOE OSTI2019

Incentive-Based Control and Coordination of Distributed Energy Resources

Higher penetration of renewable generation will increase the demand for adequate (and cost-effective) controllable resources on the grid that can mitigate and contain contingencies locally before they cause a network-wide collapse. This report details a scalable hierarchical control strategy for coordinating a vast number of heterogeneous distributed energy resources (DERs) in order to provide three ancillary grid services: frequency response, regulation, and ramping reserve. The control architecture consists of 1) a Distribution Reliability Coordinator (DRC), which allocates resource responses based on their declared flexibility, 2) aggregator controllers, which control a collection of DERs, and finally, 3) DER controllers at the individual devices. Test results are provided showing scalable performance on thousands of simulated residential DERs (air conditioners and water heaters) as well as results of a hardware-in-the-loop demonstration of commercial HVAC and microgrid equipment providing real responses in coordination with a grid simulation. Technology commercialization barriers and strategy is also discussed.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2019

Pulsed Operation of CEBAF for JLEIC Injection

JLab Electron Ion Collider (JLEIC) is planning to use the recently upgraded 12 GeV CEBAF 1497 MHz SRF CW recirculating linac as a full-energy injector for the electron collider ring. The JLEIC electron injection requires 3-4µs long bunch trains with a 20-400ms spacing in between, resulting in uneven beam loading for the CW CEBAF. With the high beam current in JLEIC collider rings, the low duty factor of injection also requires to a very high pulsed beam current from CEBAF, exacerbating the transient beam loading issue. In this paper, we will present CEBAFs detailed pulsed operation scheme for JLEIC injection, as well as some experimental results at CEBAF.

Guo, J.↗
DOE OSTI2018

High‐Resolution Receiver Function Imaging Across the Cascadia Subduction Zone Using a Dense Nodal Array

Abstract In the summer of 2017, we deployed 174 nodal geophones in the Cascadia Subduction Zone forearc with the specific aim of conducting a high‐resolution receiver function study. The dense trench perpendicular line in central Oregon with 500‐m spacing recorded continuous data for approximately 40 days. Our plate tectonic‐scale imaging results show the same features as previous broadband seismic deployments including the top of the subducting Juan de Fuca Plate, the slab Moho, and the continental Moho. Although our deployment was limited to around 40 days, the dense station spacing allowed us to image the shallow Oregon forearc in remarkable detail. In our shallow results, we image a continuous positive arrival that we interpret as the top of the accreted Siletzia terrane. We suggest that hybrid nodal/broadband deployments could be used in conjunction with offshore seismic studies to image subduction zones in unprecedented detail.

Ward, K. M.↗